.product-container {
    width: 100%;
    max-width: 100vw;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    background-color: #000;
    color: #fff;
}

/* 下载独立页(download.html):避开 fixed header(64px),内容从 header 下方开始 */
.download-container {
    width: 100%;
    max-width: 100vw;
    padding-top: 64px;
    box-sizing: border-box;
    background-color: #000;
    color: #fff;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}
.hero-section {
    position: relative;
    width: 100%;
    height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    padding-left: 10%;
    text-align: left;
    background: url('https://www.unitree.com/images/2b9855f7c43845819ab6d8156c75aeea_3840x2143.jpg') no-repeat center center;
    background-size: cover;
}
.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}
.hero-content h1 {
    font-size: 70px;
    font-weight: 500;
    line-height: 70px;
    margin-bottom: 0px;
}
.hero-content h2 {
    font-size: 45px;
    font-weight: 500;
    line-height: 45px;
    margin-bottom: 12px;
    color: #fff;
}
.hero-content .highlight {
    background: linear-gradient(45deg, #9373ff, #f2eeff);
    -webkit-background-clip: text;
    font-size: 45px;
    font-weight: 500;
    -webkit-text-fill-color: transparent;
    margin-bottom: 60px;
    display: inline-block;
}
.hero-content .btns {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
}
.hero-content .watch-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 5px;
    background: linear-gradient(#000, #000) padding-box, linear-gradient(45deg, #9373ff, #f2eeff) border-box;
    background-clip: padding-box, border-box;
    background-origin: border-box;
    border: 2px solid transparent;
    border-radius: 50px;
    cursor: pointer;
    font-size: 16px;
    padding: 10px 20px;
    -webkit-user-select: none;
    -moz-user-select: none;
    user-select: none;
    color: #fff;
    transition: all 0.3s ease;
}
.hero-content .watch-btn:hover {
    opacity: 0.8;
}
.hero-content .tip {
    font-size: 1rem;
    color: #ccc;
    font-weight: 300;
}

/* Video Modal Styles */
.video-modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(30, 30, 30, 0.95);
    z-index: 9999;
    align-items: center;
    justify-content: center;
}

.video-modal-content {
    position: relative;
    width: 80%;
    max-width: 1200px;
    background-color: #000;
    border-radius: 8px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.5);
    display: flex;
    justify-content: center;
    align-items: center;
}

.video-modal-content video {
    width: 100%;
    height: auto;
    max-height: 85vh;
    border-radius: 4px;
    outline: none;
}

.close-btn {
    position: absolute;
    top: -40px;
    right: -40px;
    color: #fff;
    font-size: 30px;
    cursor: pointer;
    transition: color 0.3s ease;
    z-index: 10000;
}

.close-btn:hover {
    color: #ccc;
}

.video-section {
    position: relative;
    width: 100%;
    height: 200vh;
}
.video-inner {
    position: sticky;
    top: 0;
    width: 100%;
    height: 100vh;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}
.video-inner video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    object-fit: cover;
}
.video-overlay {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.3);
    z-index: 2;
}
.bg-video-mask {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 4;
    background: rgba(0, 0, 0, 0.55);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    cursor: pointer;
}
.bg-video-tip {
    padding: 12px 24px;
    border: 1px solid rgba(255, 255, 255, 0.6);
    border-radius: 999px;
    font-size: 16px;
    background: rgba(0, 0, 0, 0.35);
}
.video-content {
    position: relative;
    z-index: 3;
    text-align: center;
    max-width: 900px;
    padding: 0 20px;
    opacity: 0;
    transform: translateY(100px);
    transition: opacity 1s ease-out, transform 1s ease-out;
}
.video-inner.is-visible .video-content {
    opacity: 1;
    transform: translateY(0);
}

.image-section {
    width: 100%;
    background-color: #000;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.product-full-img {
    width: 100%;
    height: auto;
    display: block;
}

/* Carousel Section Styles */
.carousel-section {
    width: 100%;
    background-color: #000;
    padding: 0;
}

.carousel-container {
    position: relative;
    width: 100%;
    height: 100vh;
    overflow: hidden;
}

.carousel-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
    display: flex;
    align-items: center;
    justify-content: center;
}

.carousel-slide.active {
    opacity: 1;
    z-index: 1;
}

.carousel-slide img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 60px;
    height: 120px;
    background-color: #0000000d;
    color: white;
    border: none;
    font-size: 24px;
    cursor: pointer;
    z-index: 2;
    transition: background-color 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
}

.carousel-btn:hover {
    background-color: #000000d9;
}

.prev-btn {
    left: 0;
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
}

.next-btn {
    right: 0;
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
}

.carousel-dots {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 10px;
    z-index: 2;
}

.dot {
    width: 30px;
    height: 3px;
    background-color: rgba(255, 255, 255, 0.5);
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.dot.active, .dot:hover {
    background-color: #fff;
}
.video-content h3 {
    font-size: 3.5rem;
    font-weight: 600;
    margin-bottom: 20px;
    text-shadow: 0 2px 10px rgba(0,0,0,0.8);
}
.video-content p {
    font-size: 1.5rem;
    font-weight: 300;
    line-height: 1.5;
    text-shadow: 0 2px 10px rgba(0,0,0,0.8);
}

.feature-section {
    padding: 100px 20px;
    text-align: center;
    background-color: #111;
}
.feature-section h2 {
    font-size: 2.5rem;
    margin-bottom: 20px;
}
.feature-section p {
    font-size: 1.2rem;
    color: #aaa;
    max-width: 800px;
    margin: 0 auto 50px auto;
    line-height: 1.6;
}

.specs-section {
    padding: 100px 20px;
    background-color: #000;
    text-align: center;
}
.specs-section h2 {
    font-size: 3rem;
    margin-bottom: 50px;
}
.specs-grid {
    display: flex;
    flex-wrap: wrap;
    max-width: 1000px;
    margin: 0 auto;
    gap: 20px;
}
.spec-item {
    flex: 1 1 calc(33.333% - 20px);
    background: #1a1a1a;
    padding: 30px;
    border-radius: 10px;
    text-align: left;
}
.spec-item h4 {
    font-size: 1.2rem;
    color: #888;
    margin-bottom: 10px;
}
.spec-item p {
    font-size: 1.5rem;
    font-weight: bold;
}

@media (max-width: 768px) {
    .hero-section {
        padding-top: 10vh;
    }
    .hero-content h1 { font-size: 3.5rem; }
    .hero-content h2 { font-size: 1.5rem; }
    .video-content h3 { font-size: 2.5rem; }
    .video-content p { font-size: 1.2rem; }
    .spec-item { flex: 1 1 100%; }
}
/* Download Section Styles */
.download-section {
    position: relative;
    width: 100%;
    height: 100vh;
    background-size: cover;
    display: flex;
    color: #fff;
    padding-top: 3px;
}

/* 下载独立页(download.html)下的 download-section:
   .download-container 已加 padding-top:64px 避开 fixed header,
   这里把高度从 100vh 调整为 calc(100vh - 64px) 避免底部溢出滚动条 */
.download-container .download-section {
    height: calc(100vh - 64px);
}

.download-sidebar {
    width: 250px;
    padding: 60px 0;
    border-right: 1px solid rgba(255, 255, 255, 0.4);
    display: flex;
    flex-direction: column;
    height: 100%;
    min-height: 0;
    box-sizing: border-box;
    overflow: hidden;
}

.sidebar-title {
    font-size: 1.2rem;
    font-weight: 300;
    margin-bottom: 30px;
    padding-bottom: 20px;
    text-align: center;
    border-bottom: 1px solid rgba(255, 255, 255, 0.4);
    width: 100%;
    color: #000;
}

.sidebar-menu {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    flex: 1 1 auto;
    min-height: 0;
    overflow-y: auto;
    width: 100%;
}

.sidebar-menu li {
    width: 60%;
    padding: 12px 0;
    background: rgba(255, 255, 255, 0.85);
    color: #333;
    text-align: center;
    cursor: pointer;
    font-size: 0.95rem;
    transition: all 0.3s ease;
}

.sidebar-menu li:hover, .sidebar-menu li.active {
    background: #fff;
    font-weight: bold;
}

.download-main {
    flex: 1;
    padding: 60px 80px;
    display: flex;
    flex-direction: column;
    min-height: 0;
    overflow: hidden;
}

.main-title {
    font-size: 1.2rem;
    font-weight: 300;
    margin-bottom: 40px;
    color: #000;
    flex: 0 0 auto;
}

/* 文件列表面板:填满 .download-main 剩余空间,内容超出时内部滚动 */
.download-panel {
    flex: 1 1 auto;
    min-height: 0;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
}

/* ============= 自定义滚动条(侧边栏分类 + 右侧文件列表) ============= */
/* Webkit 内核 (Chrome / Safari / Edge / Opera) */
.sidebar-menu::-webkit-scrollbar,
.download-panel::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

.sidebar-menu::-webkit-scrollbar-track,
.download-panel::-webkit-scrollbar-track {
    background: transparent;
    border-radius: 4px;
}

.sidebar-menu::-webkit-scrollbar-thumb,
.download-panel::-webkit-scrollbar-thumb {
    background: rgba(20, 50, 60, 0.55);
    border-radius: 4px;
    border: 1px solid rgba(255, 255, 255, 0.3);
    transition: background 0.25s ease;
}
.sidebar-menu::-webkit-scrollbar-thumb:hover,
.download-panel::-webkit-scrollbar-thumb:hover {
    background: rgba(20, 50, 60, 0.85);
}

/* Firefox */
.sidebar-menu,
.download-panel {
    scrollbar-width: thin;
    scrollbar-color: rgba(20, 50, 60, 0.55) transparent;
}

.file-list {
    list-style: none;
    padding: 0;
    margin: 0;
    width: 100%;
}

.file-list li {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.3);
}

.file-name {
    flex: 1;
    font-size: 0.95rem;
    font-weight: 300;
    color: #000;
}

.file-size {
    width: 100px;
    text-align: right;
    font-size: 0.9rem;
    color: #000;
}

.download-btn {
    margin-left: 40px;
    padding: 6px 20px;
    background: rgba(255, 255, 255, 0.85);
    color: #333;
    border: none;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.3s;
}

.download-btn:hover {
    background: #fff;
}

/* ============= 移动端响应式 ============= */
@media (max-width: 992px) {
    .hero-section {
        width: 100%;
        height: auto;
        aspect-ratio: 16 / 9;
        min-height: 0;
        box-sizing: border-box;
        padding-left: 6%;
        padding-right: 6%;
    }
    .hero-content h1 {
        font-size: 48px;
        line-height: 50px;
    }
    .hero-content h2 {
        font-size: 28px;
        line-height: 32px;
    }
    .hero-content .highlight {
        font-size: 28px;
        margin-bottom: 36px;
    }
    .video-content h3 {
        font-size: 2.4rem;
    }
    .video-content p {
        font-size: 1.2rem;
    }
    .carousel-btn {
        width: 44px;
        height: 80px;
        font-size: 18px;
    }
    .download-section {
        flex-direction: column;
        height: calc(100vh - 64px);
        min-height: 0;
    }
    .download-sidebar {
        width: 100%;
        padding: 20px 0 16px;
        border-right: none;
        border-bottom: 1px solid rgba(255, 255, 255, 0.4);
        height: auto;
        flex: 0 0 auto;
        overflow: visible;
    }
    .sidebar-title {
        margin-bottom: 14px;
        padding-bottom: 10px;
    }
    .sidebar-menu {
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px;
        flex: 0 0 auto;
        overflow: visible;
    }
    .sidebar-menu li {
        width: auto;
        padding: 8px 16px;
        font-size: 0.9rem;
        border-radius: 4px;
    }
    .download-main {
        padding: 20px 24px 30px;
        flex: 1 1 auto;
        min-height: 0;
        overflow: hidden;
        display: flex;
        flex-direction: column;
    }
    .download-panel {
        flex: 1 1 auto;
        min-height: 0;
        overflow-y: auto;
        display: block;
    }
    .main-title {
        margin-bottom: 16px;
        font-size: 1.1rem;
        flex: 0 0 auto;
    }
    .file-list li {
        padding: 14px 0;
        flex-wrap: wrap;
        gap: 8px;
    }
    .file-name {
        font-size: 0.9rem;
        flex: 1 1 100%;
    }
    .file-size {
        font-size: 0.85rem;
        width: auto;
    }
    .download-btn {
        margin-left: 0;
        font-size: 0.85rem;
        padding: 5px 16px;
    }
}

@media (max-width: 768px) {
    .hero-section {
        width: 100%;
        height: auto;
        aspect-ratio: 16 / 9;
        min-height: 0;
        box-sizing: border-box;
        padding-left: 20px;
        padding-right: 20px;
        padding-top: 80px;
        align-items: center;
        justify-content: center;
        text-align: left;
    }
    .hero-content h1 {
        font-size: 36px;
        line-height: 40px;
    }
    .hero-content h2 {
        font-size: 20px;
        line-height: 24px;
    }
    .hero-content .highlight {
        font-size: 20px;
        margin-bottom: 28px;
    }
    .hero-content .watch-btn {
        font-size: 14px;
        padding: 8px 18px;
    }
    /* 取消移动端 video sticky 效果,避免大段黑色空白 */
    .video-section {
        height: auto;
    }
    .video-inner {
        position: relative;
        top: auto;
        height: 60vh;
        min-height: 280px;
    }
    .carousel-container {
        height: 60vh;
        min-height: 300px;
    }
    .video-content h3 {
        font-size: 1.8rem;
        margin-bottom: 12px;
    }
    .video-content p {
        font-size: 1rem;
    }
    .video-modal-content {
        width: 92%;
    }
    .close-btn {
        top: -34px;
        right: 0;
        font-size: 26px;
    }
    .carousel-btn {
        width: 36px;
        height: 60px;
        font-size: 16px;
    }
    .carousel-dots {
        bottom: 16px;
    }
    .dot {
        width: 22px;
        height: 2px;
    }
    .download-main {
        padding: 20px 16px 32px;
    }
    .file-list li {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
        padding: 14px 0;
    }
    .file-size {
        text-align: left;
    }
    .download-btn {
        align-self: flex-start;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 30px;
        line-height: 34px;
    }
    .hero-content h2 {
        font-size: 18px;
    }
    .hero-content .highlight {
        font-size: 18px;
    }
    .video-content h3 {
        font-size: 1.4rem;
    }
    .video-content p {
        font-size: 0.9rem;
    }
}